1. Field of the Invention
The present invention relates to an organic electronic device, and particularly, to a photocurable pressure-sensitive adhesive composition used to encapsulate an organic electronic device, an adhesive film formed thereof, and a method for manufacturing an organic electronic device.
2. Discussion of Related Art
An organic electronic device (OED) refers to a device including an organic material layer generating the exchange of charges using holes and electrons, and for example, the OED includes a photovoltaic device, a rectifier, a transmitter and an organic light-emitting diode (OLED).
A representative OED, which is an OLED, has less power consumption and a higher response speed, and forms a thinner display device or light than a conventional light source. In addition, the OLED has excellent space utilization, and is expected to be applied in various fields including all kinds of portable devices, monitors, notebook computers and TVs.
To extend compatibility and use of the OLED, a major problem is durability. Organic materials and metal electrodes included in the OLED are very easily oxidized by external factors such as moisture, and a product including the OLED is very sensitive to environmental factors. Therefore, various methods to prevent penetration of oxygen or moisture from an external environment have been suggested.
A large-scale element has a limitation to an edge sealing method due to the deterioration of the element caused by the lack of mechanical strength and the decrease in efficiency of heat emission. Generally, an UV edge sealing or frit method in combination with a getter additionally uses a heat-curable/visible ray-curable filled adhesive, which thus makes a process complicated, resulting in an increase in cost.
In addition, while the edge sealing may improve mechanical strength and ensure a moisture barrier characteristic according to the type of filling, the edge sealing may be difficult to apply to a flexible display. The heat-curable entire surface filler is necessarily cured at low temperature to avoid damage to an element. However, since the heat-curable filler has a pot life to be cured at low temperature, processibility is degraded. The visible ray-curable filler has difficult curing conditions and a limitation to selection of a material, compared with a UV-curable filler.
In Korean Patent Publication No. 2008-0074372, a photopolymerization adhesive composition, which is present in a liquid-state at room temperature, including an epoxy resin, an acrylate resin, a cationic photopolymerization initiator and a radical photopolymerization initiator, is disclosed. When the above composition is coated on an entire surface of an organic light-emitting element, and the organic light-emitting element is assembled and encapsulated, the organic light-emitting element may be damaged due to the radiation of light. Moreover, the above method is a liquid-state method, which has many limitations.